Much of modern physics has been about exploring inherently invisible things, which seem to be far more common than the obvious things we experience with our senses. Yet these invisible things follow rigorous laws that allow us to test their existence in many ways. Here is a very short list of some of the "invisible" things that we routinely work with.
Unlike the hosannas of Palm Sunday and the yearned-for glory of Easter Day, this day in Holy Week, Holy Saturday, speaks most directly to the daily reality of our lives. After the shock of death or words that bring despair -- words like cancer, divorce, terminal, downsizing -- we find ourselves entering the dark void of unknowing.